import java.util.Scanner;

public class Test {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.next();

        char[] ch = new char[101];
        for (int i = 0; i < s.length(); i++) {
            ch[i] = s.charAt(i);
        }

        for (int i = 0; i < s.length(); i++) {
            int j;
            for (j = 0; j < i; j++) {
                if(ch[j] == ch[i]){
                    break;
                }
            }
            if(i == j){
                System.out.print(ch[i]);
            }
        }
    }
}
